Creating pneumatic launchers

[ToddF]

Originally Posted by billbo911

As long as you are taking my comments out of context, then you are right.

Sorry, Mr. Bill. I wasn't calling you out at all. Your example was right on the money. I was reacting to this post.

Originally Posted by AustinShalit

Anytime you use a large bore the speed is going to decrease. ...

In order to have an equal amount of force, use multiple cylinders with smaller bore rather than a single large bore for greater speed.

This design advise is correct in the context of FIRST robotics, assuming both cylinders are fed by valves with the max allowable Cv. But, it's not what you would normally do in industry.

At this stage of the design process, the students are coming up with a lot of different ideas for how to execute different concepts. Some of those are great ideas in the "real world", but not in a FIRST robot, because of the restrictions imposed by the rules. Some of those ideas are great for a FIRST robot, but are not what you would do in industry. I always take great pains to explain the difference because I don't want a student to internalize a "lesson learned" from the world of FIRST robotics and apply it to real world engineering when it might only be true in the context of the FIRST robot rules.

Whether it's because of imprecise language or because they have learned the wrong lessons, you see a lot of half-true design rules quoted by students (and occasionally mentors) on CD. I think as mentors we're responsible to explain to the students how these design rules are context dependent, and how the underlying assumptions affect their design decisions.

[billbo911]

Originally Posted by ToddF

... Whether it's because of imprecise language or because they have learned the wrong lessons, you see a lot of half-true design rules quoted by students (and occasionally mentors) on CD. I think as mentors we're responsible to explain to the students how these design rules are context dependent, and how the underlying assumptions affect their design decisions.

Spot on Todd!

There are MANY variables that have to be taken into account when designing a system, and this applies to almost any "system".
The language we use to communicate those ideas has to be correct, and should be thorough. Leaving out small details can lead to misunderstandings, as can been seen in this thread.

In this vein, here is what we will be doing in the next couple weeks.

We have a prototype we are satisfied with. It will be put into CAD, and then built accordingly.

Once built, we will run a couple thought experiments (Hypothesis), run several tests (Experimentation) , and then formation of our conclusions.
The goal of this is to optimize our catapult for competition based on the actual design we are using.